Attempts have conventionally been made to attain the higher packing density of parts using a lead frame. As an example of such attempts, there is a technique disclosed in Japanese Patent Application Laid-Open No.1-257361. FIG. 15 is a sectional view of the semiconductor assembly disclosed in the above-mentioned publication. Referring to FIG. 15, semiconductor elements 404, 404' are mounted on the surfaces of two lead frames 401, 401', respectively. Electrode pads on the individual semiconductor elements 404, 404' are connected to their corresponding inner leads by bonding wires 403, 403', respectively. Then, with their rear faces faced to each other, the two lead frames 401, 401' are overlaid on each other with an insulating film 405 interposed therebetween. Subsequently, the semiconductor elements 404, 404' are encapsulated with an encapsulating resin body 402. Thereafter, the outer lead pins of the two lead frames are bent in one direction. Since the outer lead pins of the two respective lead frames are bent with their different lengths, they would not come into contact with each other.